![]() |
Register or Log In To remove these advertisements. |
|
|
![]() |
|
Thread Tools | Display Modes |
|
![]() |
#1 |
Registered User
Join Date: Sep 2010
Location: Marble Falls, TX
Posts: 1,575
|
Calling all "Double Hump" crossmembers.
Thinking about upgrading to a double hump crossmember to clean up my exhaust since I'm installing headers but I'm having a bit of trouble.
So far I've found out that these trucks have them, 73-75 1/2 ton 76-79(?) 3/4 or 1 tons If that information is wrong please correct me ![]() My questions though have to do with installation. 1) So far I have read stories of people's transmissions being at different heights causing problems, will the crossmembers from the above models cause this? 2) The few pictures I have seen show supports bolted to the top of the frame, are these required or can I just skip these and have it bolted on the bottom of the frame on both sides? Any help would be appreciated. I've probably gone through 40 threads about these and most were created back in like 02 and 03 so the pictures are long gone. Any pictures would be nice too. Thanks, Michael
__________________
Michael Re-starting the neglected '77...http://67-72chevytrucks.com/vboard/s...=425464&page=9 |
![]() |
![]() |
![]() |
#2 |
Registered User
Join Date: Jun 2011
Location: Baytown TX
Posts: 2,219
|
Re: Calling all "Double Hump" crossmembers.
I converted to this crossmember without using the top braces in my 78 GMC 1/2 SWB 350ci/TH350 with no issues other than having to drill mounting hole on the lower left side frame flange. I do know they are in 73-76 1/2 tons, not sure how long they were used in 3/4 and 1 tons. I plan on using this one on my 82.
__________________
John 82 Chevy Silverado 350ci/TH350 ![]() |
![]() |
![]() |
![]() |
#3 | |
Registered User
Join Date: Sep 2010
Location: Marble Falls, TX
Posts: 1,575
|
Re: Calling all "Double Hump" crossmembers.
Quote:
__________________
Michael Re-starting the neglected '77...http://67-72chevytrucks.com/vboard/s...=425464&page=9 |
|
![]() |
![]() |
![]() |
#4 | |
Registered User
Join Date: Jun 2011
Location: Baytown TX
Posts: 2,219
|
Re: Calling all "Double Hump" crossmembers.
Quote:
Posted via Mobile Device
__________________
John 82 Chevy Silverado 350ci/TH350 ![]() |
|
![]() |
![]() |
![]() |
#5 | |
Registered User
![]() Join Date: Oct 2008
Location: Montpelier, VA
Posts: 315
|
Re: Calling all "Double Hump" crossmembers.
Quote:
I'd like to see a pic of the 3/4 x-member installed too. |
|
![]() |
![]() |
![]() |
#6 |
Just here to tinker
![]() Join Date: Jun 2008
Location: Holland, MI
Posts: 3,692
|
Re: Calling all "Double Hump" crossmembers.
I know there was just a recent thread about this not too long ago. I thought we determined that any truck with factory dual exhaust came with them. I know my '78 1/2 ton diesel has the dual hump because it had factory dual exhaust.
__________________
78 C10 SWB Diesel #1 (wrecked)http://67-72chevytrucks.com/vboard/s...1978+silverado 78 C10 SWB Diesel #2 (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=650751 60 GMC Suburban (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=445526 60 GMC 1000 (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=298235 67 GMC 1500 (sold) http://67-72chevytrucks.com/vboard/s...d.php?t=803695 86 Suburban(summer unit) http://67-72chevytrucks.com/vboard/s...d.php?t=810697 88 Suburban 4x4(winter unit)https://67-72chevytrucks.com/vboard/...25#post8900725 |
![]() |
![]() |
![]() |
#7 |
At the body shop.
Join Date: Aug 2009
Location: Land of fruits and nuts.
Posts: 5,211
|
Re: Calling all "Double Hump" crossmembers.
You can use a 3/4 ton x member on a 1/2 you will need to notch the center to keep the angles right. As 3/4 ton frame is deeper thru that area. Some minor changes to upper bracket.
Drill new holes and some tweaking where its bolts to the upper flange. Also by using a 3/4 ton makes room for 3" pipes. Posted via Mobile Device
__________________
" That didnt make it any newer " " Dont antique the equipment " |
![]() |
![]() |
![]() |
#8 |
Slots go on anything!
Join Date: May 2003
Location: Richardson, TX
Posts: 5,957
|
Re: Calling all "Double Hump" crossmembers.
I left mine off as well. Don't know if it is the right thing to do, but it seems to work.
__________________
1974 Jimmy- 5.3/4L80e/NP241 |
![]() |
![]() |
![]() |
#9 |
Registered User
![]() Join Date: Oct 2008
Location: Montpelier, VA
Posts: 315
|
Re: Calling all "Double Hump" crossmembers.
I have the double hump on my 73 Jimmy and it had the upper braces removed when I bought it and the exhaust run above the x-member. I found some uppers from later model trucks and installed them. You can use uppers from either side, they are reversible.
I felt like I needed them since the Jimmy is a full 'vert and flexes a lot. I know I had to do some fancy spreading on the frame to get all of the x-member holes to line up. I had to drop the exhaust back down to the stock location too. A non-'vert application may not need them though. |
![]() |
![]() |
![]() |
#10 |
At the body shop.
Join Date: Aug 2009
Location: Land of fruits and nuts.
Posts: 5,211
|
Re: Calling all "Double Hump" crossmembers.
![]() Like so. ![]() Posted via Mobile Device
__________________
" That didnt make it any newer " " Dont antique the equipment " |
![]() |
![]() |
![]() |
#11 |
yeller
Join Date: Oct 2001
Location: Twin Cities
Posts: 13,826
|
Re: Calling all "Double Hump" crossmembers.
I am guessing he assumed your first name was John, but didn't know if it had an H or not.
__________________
Jeff 73-87.com 73-87.com Facebook page 73-87 cab corner 6x9 speaker brackets for sale 67-72 cab corner speaker brackets for sale 47-54 cab corner speaker brackets for sale |
![]() |
![]() |
![]() |
#12 | |
Registered User
Join Date: Jun 2011
Location: Baytown TX
Posts: 2,219
|
Re: Calling all "Double Hump" crossmembers.
Quote:
Posted via Mobile Device
__________________
John 82 Chevy Silverado 350ci/TH350 ![]() |
|
![]() |
![]() |
![]() |
#13 |
Registered User
Join Date: Jul 2010
Location: Janesville, WI
Posts: 664
|
Re: Calling all "Double Hump" crossmembers.
correct, i forgot which it was but if i remember correctly it does have an "H" having been called Wayne to often in my life i assume the with or with out h thing is a major pet peeve of yours and i wanted to be sure if i couldnt do it right, that i didnt do it wrong. thanks for the measurements, do the humps line up pretty well with headers?
|
![]() |
![]() |
![]() |
#14 |
BAD BOW-Silverado XST
Join Date: May 2000
Location: Senior Member from Austin, TX
Posts: 6,431
|
Re: Calling all "Double Hump" crossmembers.
Someone on this board made me one.
![]() I have pictures of it installed. I just can't find them on my web photo album. The higher hump allows the pipes to be tucked up under the frame. Only the driveside header is seen from the side. ![]() The Chevelle headerare designed one lower than the other. My guess is to fit the starter on the other shorter header side. |
![]() |
![]() |
![]() |
Bookmarks |
|
|